Electrical apparatus



Jan. 11, 1966 H. a. GERSONI ETAL 3,228,383

ELECTRICAL APPARQTUS Filed April 1, 1965 INVENTORS HENRY B. GERSONi 44HARLEY H SCHROEDER BY gm ATTO EYS United States Patent 3,223,383Patented Jan. 11, 1955 nice 3,228,383 ELEQTRHIAL APPARATU Henry B.Gersoni, Colliersville, and Harley H. Schroeder, Sidney, N.Y., assignorsto The Bendix Corporation, Sidney, N.Y., a corporation of Delaware FiledApr. 1, 1963, Ser. No. 269,253 14- tClairnS. (Cl. 123148) This inventionrelates to electrical apparatus, and more particularly to a system, suchas an ignition system for spark ignited internal combustion engines, forgenerating electrical energy and cyclically distributing such energy toa plurality of circuits in sequence.

The invention has among its objects the provision of novel apparatus forsupplying electrical energy to a plurality of circuit means, such as thesparking plug circuits of a multi-cylinder combustion engine or thelike, in sequence and in timed relation to the rotation of a shaft suchas the crankshaft of such engine.

Another object of the invention is to provide novel apparatus of theabove character which is so constructed as to facilitate adaptation ofthe same to engines having different numbers of cylinders, or to permitthe energy supplying apparatus to be driven at different speeds withrespect to the crankshaft, with but a minimum of modification oradjustment.

A further object of the invention is to provide novelly constructeddistributing apparatus for an electrical current-generating anddistributing system, such distributing apparatus being so constructed asto be readily adapted to the ignition systems of a variety of differenttypes of internal combustion engines.

Still another object is to provide a novel magneto supplied ignitionsystem for engines in which the sparks or pulses are required at unevenintervals of crankshaft rotation or at equal intervals which exceed ordiffer from the successive magneto rotor intervals at which spark energymay be effectively supplied.

A still further object is to provide an engine ignition system of theabove type which is novelly constructed to enhance the operating life ofthe magneto circuit breaker in such engines and hence, the trouble-freeoperating life of the engine.

It is also an object of the invention to provide a novel engine ignitionsystem whereby greater energy may be made available from a given magnetofor engine starting and low engine speed operation.

Yet another object of the invention resides in the provision of novelapparatus of the type described which permits the use of the apparatuswith an engine having a lesser number of cylinders than the maximumnumber which the current-generating and distributing apparatus cansupply when driven at a given speed, such apparatus functioning with nodecrease in efiiciency when thus employed with an engine having suchlesser number of cylinders.

A still further object is to provide novel ignition apparatus which maybe applied to engines having different numbers of cylinders withoutreducing the service life of any of the parts of the system.

The above and further objects and novel features of the invention willmore fully appear from the following detailed description when the sameis read in connection with the accompanying drawing. It is to beexpressly understood, however, that the drawing is for the purpose ofillustration only and is not intended as a definition of the limits ofthe invention.

It the drawing, wherein like reference characters refer to like partsthroughout the several views,

FIG. 1 is a circuit diagram showing an ignition circuit in accordancewith the invention, such circuit being served by one coil of theschematically illustrated magneto; and

FIG. 2 is a fragmentary diagram of a modified circuit in accordance withthe invention.

The embodiment of the invention illustrated in FIG. 1 of the drawing, byway of example, is in the form of a magneto generator-distributorcombination adapted for use in a low-voltage distribution type ofignition system for a multi-cylinder internal combustion engine. Onesuch system is shown, for example, in the patent to R. B. Clark et al.,No. 2,847,590. The ignition system of the present invention representsan improvement over that disclosed in such Clark et al. patent, thesystem of the present invention being such that the magnetogeneratordistributor combination may be readily adapted for use with avariety of engines having difierent numbers of cylinders, ranging fromthe maximum number of cylinders for which the combination is designedwhen the generator is driven at a given speed with respect to the enginecrankshaft to substantially any smaller number of cylinders. Thus, forexample, the illustrative 4-pole magneto generator-distributorcombination may be employed to supply the ignition needs of an8-cylinder 4-cycle engine when the generator shaft is driven at thespeed of the crankshaft of the engine and the distributor cam shaft isdriven at one-half crankshaft speed. When such magneto generator isconnected to a distributing system such as shown in the drawing,however, the combination can supply the ignition needs of a 4-cylinder4-cycle engine when the magneto generator is still driven at crankshaftspeed. The system of the invention may be further adapted, as will beobvious to those skilled in the art, to serve the ignition needs ofother engines, such as those having an uneven number of cylinders andthose requiring sparks at uneven intervals of crankshaft rotation, bychanging the speed ratio between the crankshaft of the engine and thegenerator shaft or by changing the number of operative distributingunits connected to sparking plugs of the engine, or both. The systemalso lends itself admirably to adaptation to engines wherein it isdesired to increase the spark energy of the ignition system byincreasing the speed of the magneto generator relative to the speed ofthe engine crankshaft. The system as illustrated in the drawing may, forexample, supply the needs of an S-cylinder 4-cycle engine with increasedenergy when the generator is driven at twice the crankshaft speed. Thesystem of the invention is similarly adapted for twostroke cycle enginesby doubling the generator and crankshaft speeds.

In the drawing there is shown a magneto generator generaly designatedit), said magneto generator having a rotor 11 carrying four equallyangularly spaced poles. Rotor 11 is fixedly mounted on a driven rotorshaft 12. By way of example, shaft 12 is adapted to be connected, bymeans not shown, to the crankshaft of a 4-cylinder 4-cycle engine, suchconnecting means being such as to drive the magneto shaft 32 atcrankshaft speed, or to the crankshaft of an 8-cylinder 4-cycle engineto be driven at twice crankshaft speed. Rotor 11 rotates within ahousing (not shown), the housing carrying two pairs of stator pole shoes15' and 16 with which the poles on the rotor sequentially cooperate. Themagnetic circuits between the poles of pole shoes 15 and 16 arecompleted by coil cores 17 and 19, about which coils 20 and 21 aredisposed, respectively. In the illustrative system, only coil 20 isshown as being used; coil 21 may, for example, be connected to an outputand distributing system identical with that shown for an engine providedwith dual ignition, or it may be removed when a dual ignition system isnot required. Core 1% and poles 16 may also be eliminated or they may beretained as a magnetic keeper.

One end of coil 25 is connected to ground. The other end of such coil isconnected to a wire 22 which is branched so as to be connected to fouroperative distributing circuits or units 1, 3, 5, and 7 of the system.Such operative distributing units are sequentially energized in theproper sequence by the operation of normally closed breaker points 23 ofthe magneto generator. Breaker points 23 are repeatedly opened by afour-lobe cam 25 connected to shaft 12 of the magneto generator so as torotate therewith. The cams 32 32 32 and 32" of the distributing unitsare fixedly connected to a cam shaft 34 so as to rotate therewith. Shaft34 may be connected to the rotor shaft 12 so as to rotate at one-halfthe speed of such shaft and thus in suitable ratio with the four-lobecam 25. As stated, breaker points 23 are normally closed, being springpressed toward the closed position shown. A wire 24, which is connectedto the movable contact of breaker points 23, is connected to wire 22 andhence to one end of coil 20. A wire 26 extends from the fixed contact ofthe breaker points to ground, and thus to the grounded end of coil 2%.Connected in shunt with the breaker points 23 is a condenser 27 whichminimizes arcing between the breaker points when the points are openedby cam 23.

During rotation of magneto rotor 11, a relatively low alternatingvoltage is generated in coil 20 when breaker points 23 are closed, thusproviding a closed circuit through the coil 2%). At the proper time inthe rotation of the rotor 11 relative to the stator pole shoes, thebreaker points 23 are opened by cam 25, thereby producing a surge ofcurrent in wire or bus bar 22. Such operation is repeated four timesduring each revolution of the 4-pole rotor 11 and cam 25. The systemshown is provided with a wire 2? and an interposed manually operatedswitch 30 which are connected in shunt with breaker points 23, wherebyto render the electrical system ineffective, when the switch is closed,to supply energy to the sparking plugs which are operatively connectedto the output end of wire 22 in a manner to be described.

As above noted, the illustrative system has four operative distributingunits 1, 3, 5, and 7 which are associated with the respective sparkingplugs of a 4-cylinder 4-cycle engine. Since such units ll, 3, 5, and 7are identical, a detailed description of unit 1 will sufiice. Parts inunits 3, 5, and 7 which are similar to those in unit 1 are designated bythe same reference character with an appropriate different exponent.Unit 1 has a normally open contactor 31 which is intermittently closedby a single lobed cam 32 fixedly mounted on shaft 34. The lower movablecontact 36 is connected to ground. The upper fixed contact 37 isconnected to wire 22 through the primary winding 39 of a voltage step-uptransformer 43 The secondary winding 41 has one end thereof connected toground as shown, and the other end connected to a first electrode of asparking gap or plug 35 The other electrode of such sparking gap isconnected to ground. Cam 32 is so oriented on shaft 3 1 that contactor31 is closed shortly before gap 35 is to be fired and permitted to openshortly after a discharge has occurred across gap 35 With contactor 31closed, a surge of current is delivered by the magneto generator throughwire 22 into primary winding 39 and thence to ground through the closedcontactor 31 Such surge of current through primary winding 39 induces ahigh voltage in secondary winding 41 of the transformer, such voltagebeing high enough to cause a spark discharge to occur at gap 35 Suchenergization of the distributing unit and the discharge of itsrespective spark gap is repeated in the proper timed sequence in each ofdistributing units 1, 3, 5, and 7.

The magneto generator is designed to normally supply the ignition needsof an S-cylinder 4-cycle engine when its rotor is driven at engine speedin combination with eight separate distributor units like unit 1described above. However, when the rotor speed is doubled to increasethe available energy for starting and slow speed operation or when thegenerator is connected to a 4-cylinder 4-cycle engine and is driven atcrankshaft speed, it produces twice the number of energy surges in wire22 as are required in the operation of the engine and alternate surgesare unused. In the 4-cylinder system, the unused surges occurintermediate the surges which successively energize units ll, 3, 5, and7. The system of the present invention provides novel means whereby suchunused surges are dissipated without deleteriously affecting theenergization of units 1, 3, 5, and 7 or appreciably shortening theuseful life of any of the components of the system.

The energy dissipating means shown in FIG. 1 includes four cam andcontactor units 2, 4, 6, and 8 which may be parts of a magnetogenerator-distributor such as that shown in the Clark et al. patent, No.2,847,590, as conventionally made for use with an 8-cylinder 4-cycleengine wherein the generator is driven at the speed of the enginecrankshaft. Units 2, 4, 6, and 8 are similar and hence only unit 2 isdescribed. It includes a normally open contactor 31 and a cam 32 affixedto shaft 34 for closing its contactor shortly before the occurrence ofthe surge of energy generated by the magneto after contactor 31 isopened.

One contact of contactor 31 is connected to ground and the other contactof such contactor is connected to a wire 45. Wire 45 is connected towire 22 through a series connected inductance 42 and resistor 44, theinductance being preferably wound on a core of magnetic metal.Inductance 42 and resistor 44 are so chosen that together they producean impedance which, when subjected to a current pulse from the generatorthrough wire 22, will result in a voltage wave shape across points 23and hence a flow of current between said points as the same areseparated which similates the same voltages and currents which occurwhen units 1, 3, 5, and 7 are energized. The cams of units 2, 4, 6, and8 are so oriented with respect to shaft 34- that such units successivelyreceive and dissipate the energy of surges generated by the magnetointermediate those which energizes units 1, 3, 5, and 7 for firing thespark plugs. Because of the impedance match mentioned above, conditionswithin the system, including those at breaker points 23, aresubstantially the same Whether the system is delivering an energy surgeto one of the distributing units 1, 3, 5, and 7 or is delivering a surgeto one of the cam and contactor units 2, 4, 6, and 8 thence to theenergy dissipating impedance 4 2, 44. It will be seen that without thematching energy dissipating units and with distributor units 1, 3, 5,and 7 all receiving alternate surges of like polarity, the transfer ofmetal from one contact of magneto breaker 23 to the other, due toarcing, would occur in one direction only or unevenly in one direction.This would result in a substantial reduction in the operating life ofthe breaker contacts, a result which is avoided by the presentinvention.

An alternative system in accordance with the invention is fragmentarilyshown in FIG. 2. In such alternative system the cam and contactor units2, 4, 6, and 8 and wire 45 are omitted from the system of FIG. 1 and oneof such units is replaced by the cam and contactor unit 46 shown in FIG.2. Unit 46 includes a four-lobe cam 47 affixed to shaft 34-, cam 47 closng a normally open contactor 49 four times during each revolution ofshaft 34. The cam 47 is so oriented with respect to the cams ofdistributing units 1, 3, 5, and 7 that contactor 43 is closed to receiveeach of the unused energy pulses generated by the magneto. The movablecontact of contactor 49 is connected to ground; the other is connectedto wire 22 of the modified system of FIG. 1 through series connectedinductance 42 and resistor 44. As will be apparent from the above, thesystem of FIG. 2 functions electrically in the same manner as that ofFIG. 1, the essential difference between the two systems being the useof a single cam and contactor unit in FIG. 2 to direct unwanted surgesto the energy dissipating unit 42, 44 rather than the four cam andcontactor units employed in FIG. 1.

It has been found that the use of an energy dissipating unit 42, 44,having an eifective impedance substantially equalling the effectiveimpedance of each of the transformer circuits of units 1, 3, 5, and 7,does not decrease the efiectiveness of the system in delivering energyto the operative distributing units but does result in an increase inthe service life of the magneto circuit breaker. When unwanted energypulses of-a similar system are dissipated in the generator circuit, withor Without an added resistance, it has been found that the voltage waveform of the positive and negative pulses appearing across the points ofbreaker 23 are markedly dissimilar. This results in undue arcing at thebreaker points of the magneto and in the transfer of a greater amount ofmetal in one direction between such points than in the other direction.When it is attempted to minimize such arcing by an increase in thecapacity of the condenser 27 of FIG. 1 which is connected in shunt withthe breaker points, a noticeable decrease in the output voltage of themagneto and thus a decrease in the efiiciency of the system occur.

As above set forth, the effective impedance of the energy dissipatingunit 42, 44 is made at least substantially to equal and preferablyequals the effective impedance presented by a circuit comprisingtransformer 46 In one satisfactory commercial system made in accordancewith the invention, the inductance 42 employs an open magnetic coreinductor having a coil composed of 279 turns of #22 wire and theresistor 44 is a 2 ohm watt resistor. The breaker point shuntingcondenser 27 in such embodiment has a capacity of 0.95 at. when bothcoils 2t) and 21 of the magneto are operatively employed. When coil 21is not used and a magnetic keeper is substituted for core 19, thecondenser 27 in such embodiment preferably has a capacity of 1.2 ,uf.

As above indicated, the system of the present invention may also be usedadvantageously when the speed at which the magneto is driven isincreased to secure a higher magneto output voltage. Such increase ofmagneo speed results in the production of a number of unused energysurges or pulses during each rotation of the rotor of the magneto. Suchunwanted pulses are conveniently dissipated by use of a system inaccordance with the present invention. Since magnetos are convenientlyconstructed to generate an even number of evenly spaced surges duringeach revolution of the rotor, the adaptation thereof to engines havingan uneven number of cylinders or a firing order of the spark plugswherein the successive intervals between sparks are not the same incrankshaft degrees necessitates the generation of some unused, unwantedsurges which may be satisfactorily dissipated in accord' ance with thepresent invention.

Although only a limited number of embodiments of the invention areillustrated in the accompanying drawing and described in detail in theforegoing specification, it is to be expressly understood that theinvention is not limited to the details of construction thus illustratedand described. For example, the system of FIG. 1 may be modified byconnecting wires 22 and 45 directly together and by using a separateenergy dissipating unit 42, 44 with each of units 2, 4, 6, and 8, eachsuch energy dissipating unit being connected in series with thecontactor of its respective unit, 2, 4, 6, and 8. Likewise, although theinductance 42 and the resistor 44 have been shown and described as beingseparate and connected in series, a satisfactory energy dissipating unitmay be made wherein the winding of the inductance is composed eitherWholly or partially of resistance wire, such inductance having animpedance which is the same as that yielded by the described unit 42,44. Various other modifications, including changes in the design andarrangement of the parts illustrated, will now be apparent to thoseskilled in the art and may be made Without departing from the spirit andscope of the invention.

What is claimed it:

1. In an ignition system a source of successive pulses of electricalenergy comprising an induction coil and a normally closed circuitbreaker connected across said coil and adapted to be periodically openedto initiate said pulses, first and second parallel connected branchcircuits connected to said coil in parallel with said circuit breaker,said first branch circuit comprising the primary winding of atransformer. the secondary Winding of which is operatively connected tothe terminals of a spark gap, and said second branch circuit comprisingimpedance means consisting of a combination of inductance andresistance, a normally open contactor in each of said branch circuits,and means for selectively closing and opening said contactorssequentially in timed relation to the opening of said circuit breaker,said impedance means having such relation to the effective impedance ofsaid first branch circuit that the voltage wave form across the circuitbreaker as it opens will be generally the same irrespective of whichbranch circuit has its contactor closed.

2. An ignition system as defined in claim I wherein said voltage waveform is of one polarity when the contactor in the first branch circuitis closed and of the opposite polarity when the contactor in said secondbranch circuit is closed.

3. In an ignition system for combustion engines, an ignition coilcomprising a primary winding and a secondary winding, a spark gapconnected across said secondary winding, a first normally open contactorconnected in series with said primary winding, a second normally opencontactor and impedance means connected in series with each other and inparallel with said series connected primary winding and first contactor,said impedance means comprising a combination of inductance andresistance, means for successively closing and opening said contactorsin sequence, and means including a normally closed circuit breaker forsupplying a surge of current through each of said contactors upon theopening of said circuit breaker whereby a spark is created at said sparkgap by the surge occurring while said first contactor is closed and theenergy of the surge occurring while said second contactor is closed iseffectively dissipated by said impedance means, the latter being such asto effectively match the corresponding impedance of the circuitincluding said first contactor and primary winding, whereby the waveform of the voltage across the contacts of the circuit breaker when itopens is generally the same except for polarity in both instances.

4. In the combination of a spark ignition internal combustion enginehaving a crankshaft and a plurality of cylinders, a spark gap associatedwith each cylinder, a magneto having a stator and a rotor and meansdriving the magneto rotor in synchronism with the engine crankshaft, themagneto producing a number of surges of electrical energy during eachcomplete cycle of the engine which is in excess of the number ofcylinders of the engine, the improved ignition system which comprisescurrent distributing means connected to the output of the magneto, meansto operate the distributing means at predetermined times in the enginecycle to fire the spark gaps in sequence, first circuit means havingsubstantial impedance connecting the distributing means to the sparkgaps, and means to dissipate the excess surges of electrical energywhich are not employed to energize the spark gaps, said last-named meanscomprising second circuit means connected to the output of the magneto,said second circuit means being normally open, means to close saidsecond circuit means shortly before each excess surge is generated bythe magneto and means connected to the second circuit means and havingan impedance which closely approximates the impedance of the firstcircuit means to dissipate the energy of said excess surges ofelectrical energy.

5. A timed ignition system comprising a magneto having a stator and arotor, the rotor being adapted to be connected to an engine to rotate insynchronism therewith, an output circuit connected to the magneto, themagneto producing a predetermined number of surges of electrical energyduring each revolution of the rotor,

current distributing means connected to the output of the magneto, meansto operate the distributing means at predetermined times in the enginecycle, a spark gap for each cylinder of the engine, first circuit meanshaving substantial impedance operatively connected the distributingmeans to the spark gaps, the magneto producing a number of surges ofelectrical energy during each complete engine cycle which is in excessof the number of spark gaps, and means to dissipate the excess surges ofelectrical energy which are not employed to energize the spark gaps,said last-named means comprising second circuit means connected to theoutput of the magneto, said second circuit means being normally open,means to close said second circuit means shortly before each excesssurge is generated by the magneto and means associated with the secondcircuit means to dissipate the energy of said excess surges ofelectrical energy, said last-named means having an impedance whichclosely approximates the impedance of the first circuit means.

6. In ignition apparatus, a magneto generator comprising an inductioncoil, a normally closed circuit breaker connected across said coil,means for inducing current flow in said coil and means to intermittentlyopen said circuit breaker to initiate surges of electrical energy insaid coil, first circuit means for dissipating the energy of some ofsaid surges comprising a first normally open contactor and impedancemeans connected in parallel with said circuit breaker across saidinduction coil, means for intermittently closing said first contactorshortly before the opening of said circuit breaker to thereby directsurges of electrical energy through said impedance means, second circuitmeans including the primary winding of a transformer and a secondnormally open contactor connected in parallel with said circuit breakeracross said coil, the secondary winding of the transformer beingconnected across the electrodes of a spark gap, and means for closingand opening said last-named contactor in sequence with the closing andopening of said first contactor shortly before the opening of saidcircuit breaker, the impedance of said circuits being such that the waveform of the voltage across the circuit breaker and the magnitude of thecurrent flow between the circuit breaker contacts as the latter arebeing separated is substantially the same independently of whichcontactor is closed.

'7. Ignition apparatus as defined in claim 6 wherein said impedancemeans consists of a combination of an inductive winding with substantialresistance.

8. In an ignition system for a multi-cylinder combustion engine having aspark plug in each cylinder adapted to be fired by pulses of electricalenergy, a magneto riven by the engine to generate electrical energypulses in excess of the number of pulses required to fire said sparkplugs, said magneto comprising an induction coil, means for inducingcurrent flow in said coil and a periodically operated circuit breakerconnected across said coil, whereby a said energy pulse is generatedupon each opening of said circuit breaker, and circuit means connectedto the output of said coil in parallel with said circuit breaker fordissipating the energy of said excess pulses, said circuit meansconsisting of impedance means and normally open contactor means forintermittently connecting said impedance means to said output of themagneto coil Whenever a said excess pulse is generated upon the openingof said circuit breaker.

9. An ignition system as defined in claim 8 wherein said impedance meanscomprises an inductive winding having substantial resistance in theturns thereof.

ltl. An ignition system as defined in claim 8 wherein said impedancemeans comprises a resistance connected in series with an inductancewinding.

11. An ignition system as defined in claim 10 wherein said inductancewinding is wound on a metallic core.

12. In the combination of a spark ignition internal combustion enginehaving a driven shaft and at least one cylinder, a spark gap associatedwith each cylinder, a magneto having a stator, a rotor, an inductioncoil and normally closed breaker points connected in shunt with theinduction coil, means for driving the rotor in synchronism with theengine shaft, and means to open the breaker points at predeterminedtimes in the rotation of the rotor to initiate surges of electricalenergy, the magneto producing a number of surges of electrical energyduring each complete cycle of the engine which is in excess of thenumber of cylinders of the engine, the improved ignition system whichcomprises current distributing means connected to the magneto coil,first circuit means having substantial impedance connecting thedistributing means to the spark gaps, and means to dissipate the excesssurges of electrical energy generated by the magneto, said last-namedmeans comprising a second circuit means connected to the magneto coil,means to close said second circuit means shortly before each excesssurge is generated by the mag-neto and means associated with the secondcircuit means and having an impedance which closely approximates theimpedance of the first circuit means to dissipate the energy of saidexcess surges of electrical energy.

13. An ignition system as defined in claim 12 wherein the first circuitmeans comprises a transformer having substantial inductance andresistance.

14;. An ignition system as defined in claim 13 wherein the energydissipating means comprises a combination of inductance and resistancewhich substantially matches the impedance of said first circuit.

References Cited by the Examiner UNITED STATES PATENTS 2,230,508 2/1941Beer et al 1233 1 8 2,790,914 4/1957 Dingman 123148 MARK NEWMAN, PrimaryExaminer.

RICHARD B. WILKINSON, Examiner.

1. IN AN IGNITION SYSTEM A SOURCE OF SUCCESSIVE PULSES OF ELECTRICALENERGY COMPRISING AN INDUCTION COIL AND A NORMALLY CLOSED CIRCUITBREAKER CONNECTED ACROSS SAID COIL AND ADAPTED TO BE PERIODICALLY OPENEDTO INITIATE SAID PULSES, FIRST AND SECOND PARALLEL CONNECTED BRANCHCIRCUITS CONNECTED TO SAID COIL IN PARALLEL WITH SAID CIRCUIT BREAKER,SAID FIRST BRANCH CIRCUIT COMPRISING THE PRIMARY WINDING OF ATRANSFORMER THE SECONDARY WINDING OF WHICH IS OPERATIVELY CONNECTED TOTHE TERMINAL OF A SPARK GAP, AND SAID SECOND BRANCH CIRCUIT COMPRISINGIMPEDANCE MEANS CONSISTING OF A COMBINATION OF INDUCTANCE AND